This invention relates to an applicator for the non-invasive transcutaneous delivery of a medicament and more particularly to a self-contained electrophoretic applicator of compact and conformable design for the controlled delivery of a medicament.
The delivery of medicament through a person's skin utilizing electrophoresis is well known where the drug is one whose molecules are ionic in solution or suspension. The solution or suspension is made subject to an electric field and if the electrode having the same charge as that of the ions is above the solution adjacent the skin which is the site of administration, the ions will be repelled and migrate through the skin into the blood stream.
A variety of problems associated with this technique have limited severely the extent of its use even though in many cases it is highly advantageous to be able to deliver the drug at a controlled rate. Equipment available for the electrophoretic administration of a medicament is generally bulky and expensive thereby largely limiting its use to medical offices requiring the attention of technicians. Reference to or disclosure of such apparatus is shown in the following U.S. Patents where it will be noted that there is great emphasis in developing electrodes which are disposable and/or more effective:
______________________________________ 2,492,155 4,141,359 4,250,878 3,163,166 4,166,457 4,273,135 3,289,671 4,239,052 4,367,745 3,677,268 4,243,052 ______________________________________
It will be noted from U.S. Pat. Nos. 3,289,671 and 4,141,359, in particular, that rate of drug delivery is a function of current flow and that control over current flow is crucial to having the correct amount of medicament applied.
Inasmuch as it is seen that the use of this electrotherapy is limited to medical facilities, the costs involved in this mode of treatment are a direct function of the time spent using the equipment, i.e., the time it takes to administer the medicament. Consequently there is great emphasis on delivering the drug as quickly as possible, resorting to the highest permissible rate of current flow. The most effective application of systemic drugs is where it is delivered into the blood stream at a very constant and low rate over a long period of time, i.e., perhaps from one or more hours up to days. In such a situation it is seen that present apparatus and methods for using electrophoresis for the application of medicaments are just not feasible.
There have been attempts to provide apparatus for such electrotherapy which is self-contained, so that the patient can wear the device carrying on normal activities while the drug is being administered. Devices of this type are disclosed in U.S. Pat. Nos. 385,556, 486,902, and 2,784,715. These devices are bulky, expensive, and do not provide for adequate control over the rate of delivery nor time over which the drug is delivered.